1. Field of the Invention
This invention relates to an ignition switch and brake interlock for controlling operation of a transmission gear selector.
2. Description of the Prior Art
Conventional ignition switch interlocks for transmission gear selectors prevent movement of the selector from the park position to any other position when the ignition switch is in a locked state or accessory state. The interlock prevents a gear shift from the park position except when the ignition switch is at the run or off position. An interlock of this type is described in the 1989 Car Shop Manual Published by Ford Motor Company. The effects of application and release of a foot brake pedal can be incorporated in the ignition key interlock so that the gear shift lever cannot be moved from the park position when the ignition switch is in the lock or accessory position, unless the brake pedal is applied.
In addition to the components of a conventional interlock system, an electrical solenoid is connected and disconnected from a circuit containing an electrical power source, in accordance with the applied and released state of the brake pedal. A steel cable passing through the solenoid connects a lever located adjacent the ignition switch and a pivoting cam located in the gear shift mechanism. The solenoid includes a movable plunger which is magnetically locked to the seat when the electric circuit is closed and released magnetically when the circuit is open. Generally in systems of this type, a solenoid plunger is fixed to the cable by crimping at a fixed location. When tension force is applied to the cable by attempted movement of the shift selector button, the button tends to force the plunger out of contact with the seat in opposition to the magnetic forces opposing this action.